Solid core door



Feb. 9, 1965 W. B. GILBERT SOLID CORE DOOR Filed March 15, 1962 l8 l0 l6 //I l a /f r U]J- 1 x0211. 1/7 J J /4 0 xiv-nerve);

United States Patent Office 3,168,763 SOLID CQRE DOOR William B. Gilbert, Detroit, Mich, assignor to Lifetime Door Co. of Mich, a corporation of Michigan Filed Mar. 13, 1962, Ser. No. 179,358 4 Claims. (Cl. 20-35) This invention relates to panels formed with solid wood cores faced on both sides with hard sheet material and more particularly to doors formed in this manner.

One type of solid core door which is presently used employs a core or slug formed of a plurality of elongated wooden blocks disposed parallel to one another and laminated together with adhesives. This slug is disposed within a rectangular lumber frame and then covering members formed of sheets of plywood, hard-board, or the like, are laminated to each side. In forming such a door, great care must be taken in finishing those surfaces of the slug which contact the covering sheets in order to prevent the imperfections and discontinuities in the slug, including the joints between adjacent blocks, from telegraphing through the outer sheet surfacing and impairing the appearance of the door. The quality of the lumber used in forming the slug must also be carefully controlled as broken edges and the like will prevent the obtaining of a perfect finish of the slug. While the use of a relatively well-finished core and thick outer sheets may prevent defects from marring the surface of such a door at the time'it is initially installed, dimensional variations in the sheets and core resulting from temperature and moisture changes will often cause minor core defects to become apparent after long periods of time. It is a primary object of the present invention to provide a door, and a method of forming such doors, which will obviate the need for providing a carefully finished slug formed of neatly fitted blocks. The door of the present invention and the process of forming it are such as will prevent the defects in a roughly finished core formed of imperfect blocks from impairing the appearance of the finished door at any time.

In a preferred embodiment of the invention, which will subsequently be described in detail, a slug is formed of a plurality of parallel elongated blocks of wood laminated together and trimmed into a rectangular form. Both surfaces of this slug are covered with sheets of corrugated cardboard. The finished slug is then disposed within a rectangular frame which has a thickness which is greater than that of the blocks used in the slug but less than the thickness of the finished slug including both the blocks and the two sheets of cardboard. Two outer finishing sheets, preferably formed of plywood, are then laminated to the block under pressure so as to abut the surfaces of the frame and compress the slug on both sides. In this manner the plywood sheeting does not contact the blocks of the slug directly but rather only contacts the resilient cardboard. This not only prevents defects in the core from telegraphing through to the outer sheeting but also provides a door having superior sound insulation qualities as a result of the air space Within the corrugated board.

The unique construction provides a lower cost door than the conventional technique because of the savings associated with the use of a roughly finished core, as Well as insuring a smooth outer finish.

Other objects, advantages, and applications of the pres ent invention will be made apparent by the following detailed description of a preferred embodiment of the invention. The description makes reference to the accompanying drawings in which: 7

PEG. 1 is a perspective view of a panel formed in accordance with the present invention which is suitable for use as a door;

3,168,763 Patented Feb. 9,1965

FIG. 2 is an elevation view, broken away to disclose the method of construction of the door;

FIG. 3 is a cross section view taken along line 33 of FIG. 2; and

FIG. 4 is a cross section view of the components to an unfinished door disclosing the method of forming the door.

Referring to the drawings, a slug is prepared by first aligning a plurality of elongated wooden blocks 10. The rectangular blocks are of a generally uniform thickness in Width and are of various lengths. The blocks it normally have a different width than thickness and their width will be an integral divisor of the total width of the slug so that trimming of the edges to achieve a proper width will be unnecessary. The blocks 10 are initially laid so that their length exceeds the length of the finished slug.

After proper assembly of the blocks, both their upper and lower surfaces are coated with an adhesive and are then covered by sheets of resin impregnated kraft corrugated board 12. The cardboard 12 is formed in any normal manner such as a corrugated section 14 sandwiched between two plane sections 17. The cardboard 12 is preferably impregnated with a water-proofing resin.

This slug is lightly compressed in order to achieve the lamination. It is then allowed to dry. Subsequently, the edges are trimmed in a sawing operation in order to achieve the exact slug length. i

Independently, a frame is prepared composed of a pair of vertical wooden members 16, termed stiles, which are joined at their extreme ends by a pair of rails 18 of similar cross section. The frame members may be joined together in any suitable manner such as with adhesives, nails or staples. The dimensions of the stiles 16 and the rails 18 are such as to accurately accommodate the slug formed of the wooden blocks 19 and the cardboard 12..

The thickness of the frame members 16 and 18 is greater than the thickness of the blocks 19 which form part of the slug, but is less than the thickness of the entire slug formed with the blocks 10 and the corrugated board 12. By way of example, a particular door is formed with a frame thickness of 1 /2 inches. The blocks 10 employed in forming the slug are 1% inches in thickness. The uncompressed thickness of the cardboard members 12 are each approximately A of an inch. Therefore, the total thickness of the uncompressed slug is 1% inches in thickness.

The slug is disposed within the frame and is coated with an adhesive. It is then covered with top and bottom sides by sheets 20 which are preferably formed of plywood but may also be formed of other sheet material such as pressed board.

The sheets 20 are rectangular and have the same outer dimensions as the frame. As may be seen in FIGS. 3 and 4, the sheet members 20 are brought into abutment with the sides of the frame members 16 and 18 and thereby compress the corrugated sheets 12. The sheets 20 are laminated to the slug and frame sections under pressure so as to form a solid panel as illustrated in FIG. 1.

Since the sheets 20 are only in contact with the frame members and with the corrugated board 12, even gross imperfections in the slug will not be visible from the outer sides of the panel since the corrugated board 12 acts as a buffer to physically insulate the sheets 2% from the core. The corrugated board also acts as both a sound and a heat insulation since the air contained therein is a relatively poor conductor of both sound and heat.

Having thus described my invention, I claim:

1. A panel construction including:

a hollow frame;

a core having outer dimensions complementary to the and a pair of outer panels having outer dimensions similar to the frame abutting the faces of the frame and the core so as to compress the core.

2. The structure of claim 1, in which the core inner member is formed of a plurality of elongated rectangular lumber members having substantially uniform thickness and varying lengths disposed with their axes parallel to one another, the edges of said inner member being uniformly terminated so as to provide outer dimensions complementary to the dimensions of said frame.

3. A panel construction including:

a hollow frame;

a core having outer dimensions complementary to the inner dimensions of the frame disposed within said frame,

said core being composed of a solid planar rectangular inner member formed of a plurality of elongated lumber sections having similar cross sections and varying lengths disposed with their axes parallel to one another and a pair of compressible sheets having outer dimensions complementary to the frame fixed to the faces of the inner member with adhesives so as to form a unitary core, said inner member having a thickness less than that of the frame and said compressible sheets having an uncompressed thickness sufiicient to bring the total thickness of the core to a dimension which exceeds the thickness of the frame;

and a pair of outer panels having outer dimensions similar to the frame abutting the faces of the frame and the core so as to compress the core.

4. Adoor panel including: a rectangular frame formedof a pair of elongated lumber stiles joined at their extreme ends by a pair of shorter lumber rails, the stiles and rails having a uniform thickness;

a slug having outer dimensions which are complementary to the inner dimensions of the frame disposed within the frame, said slug being composed of a rectangular inner member formed of a plurality of elongated rectangular blocks having similar cross-sections and varying lengths disposed with their central axes parallel to one another, and having a thickness equal to the thickness of the blocks, such thickness being less than the thickness of the frame members, and a pair of corrugated rectangular cardboard sheets of the same outer dimensions as the inner member laminated to the opposed faces thereof, said sheets having such thicknesses that the total uncompressed slug thickness is greater than the thickness of the frame;

and a pair of rectangular plywood panels having outer dimensions similar to the frame laminated to the two faces of the frame and slug in abutting relationship to the frame surfaces so as to compress the cardboard,

whereby the plywood panels do not directly contact the inner member of the slug.

References Cited in the file of this patent UNITED STATES PATENTS 1,710,108 Onrock Apr. 23, 1929 2,006,232 Upson June 25, 1935 2,511,620 Clements June 13, 1950 2,662,043 Clements Dec. 8, 1953 FOREIGN PATENTS 749,647 Great Britain May 30, 1956 

1. A PANEL CONSTRUCTION INCLUDING: A HOLLOW FRAME; A CORE HAVING OUTER DIMENSIONS COMPLEMENTARY TO THE INNER DIMENSIONS OF THE FRAME DISPOSED WITHIN SAID FRAME, SAID CORE BEING COMPOSED OF A SOLID PLANAR RECTANGULAR INNER MEMBER HAVIING A THICKNESS LESS THAN THAT OF THE FRAME, AND A PAIR OF COMPRESSIBLE RECTANGULAR SHEETS FIXED TO THE OPPOSITE FACES OF THE INNER MEMBER, SAID SHEETS HAVING SUCH UNCOMPRESSED THICKNESS SUFFICIENT TO BRING THE TOTAL THICKNESS OF THE CORE TO A DIMENSION WHICH EXCEEDS THE THICKNESS OF THE FRAME, AND A PAIR OF OUTER PANELS HAVING OUTER DIMENSIONS SIMILAR TO THE FRAME ABUTTING THE FACES OF THE FRAME AND THE CORE SO AS TO COMPRESS THE CORE. 